Hi, I have already done OCR projects before but Arabic Language is so difficult that I think your budget is quite low. However I can do your project for you, but not on Google App Engine as it only offers limited support and runs natively on Google Hardware using Python. What I can make for you is a Windows application that recognizes Arabic characters for $1,200. The accuracy should be 80% at least and if you want it on the web, you can install it on a Windows Server and configure for script. In the case you want further optimization for accuracy, we can do more training for the arabic characters but this may take up to 20 more days and would cost an additional $800. If you have any questions, do let me know.
Thanks.